Sargassum thunbergii Extract Attenuates High-Fat Diet-Induced Obesity in Mice by Modulating AMPK Activation and the Gut Microbiota

Abstract

Sargassum thunbergii (Mertens ex Roth) Kuntze (ST) is a brown alga rich in indole-2-carboxaldehyde. This study aimed to investigate the anti-obesity effects of ethanol extract from ST in in vitro and in vivo models. In 3T3-L1 cells, ST extract significantly inhibited lipid accumulation in mature adipocytes while lowering adipogenic genes (C/epba and Pparg) and enhancing metabolic sensors (Ampk, Sirt1), thermogenic genes (Pgc-1a, Ucp1), and proteins (p-AMPK/AMPK and UCP1). During animal investigation, mice were administered a chow diet, a high-fat diet (HF), or an HF diet supplemented with ST extract (at dosages of 150 and 300 mg/kg bw per day) for 8 weeks (n = 10/group). ST extract administration decreased weight gain, white adipose tissue weight, LDL-cholesterol, and serum leptin levels while improving glucose intolerance. In addition, ST extract increased the expression of Ampk and Sirt1 in adipose tissue and in the liver, as well as p-AMPK/AMPK ratio in the liver, compared to HF-fed mice. The abundance of Bacteroides vulgatus and Faecalibacterium prausnitzii in the feces increased in response to ST extract administration, although levels of Romboutsia ilealis decreased compared with those in HF-fed mice. ST extract could prevent obesity in HF-fed mice via the modulation of AMPK activation and gut microbiota composition.

Scytosiphon lomentaria Extract Ameliorates Obesity and Modulates Gut Microbiota in High-Fat-Diet-Fed Mice

“…The following scan source parameters were used: 4000 V, VCap, and 175 V, Fragmentor. The same method was used to inject quercetin as the standard for the calculation [ 28 ].…”

“…The cell viability was quantified by Cell Titer Solution (MTS, Promega, Madison, WI, USA). The cells were seeded at 5000 cells/well (96-well), and next day, the cells were treated with SL extracts (0–100 mg/L) for 48 h. The MTS solution was then added for 2 h, and the absorbance was measured using a microplate reader at 490 nm (Multiskan™ GO, Thermo Fisher, Waltham, MA, USA) [ 28 ].…”

“…The cells were then cultured in DMEM containing 10 µg/mL insulin (Days 3–6). The SL extract (0–20 mg/L) was added to the medium throughout the 6 days of cell differentiation period [ 28 ]. Oil Red O (ORO) assay was used to determine the lipid content in the differentiated 3T3-L1 cells [ 29 ].…”

“…At the end of the treatment (Day 7), cells were fixed, ORO solution was added, and microscopy images were taken (JP/BX-FLA; Olympus, Japan). To quantify lipid content, the relative ORO concentration was determined at 500 nm [ 28 ].…”

“…After acclimating for one week, mice were randomly separated into four groups: (1) chow diet (Con), (2) high-fat diet (HF), (3) HF with low-dose SL (150 mg/kg; HF-SLL), and (4) HF with high-dose SL (300 mg/kg; HF-SLH). The Con group was fed multigrain diet (Orient, 5L79) for eight weeks, whereas the HF and experimental SL groups were administered an HF (60 kcal% fat, D12492, Research Diets, New Brunswick, NJ, USA) [ 28 ]. For eight weeks, the Con and HF groups received 100 μL of PBS orally gavaged daily, while the SL extract groups received 150 mg/kg body weight (bw; HF-SLL) or 300 mg/kg bw (HF-SLH) of SL extract.…”